Piezo-electric control device for clock work and the like timing systems

ABSTRACT

A piezo-electric control device more particularly for clockwork. A vibrating rod is mounted at one end by means of a dielectric on the free end of a piezo-electric rod, the other end portion of which is supported by a dielectric and flexible elastic bushing on a support adapted to be secured to the mounting plate of a watch or the like. Electrodes are applied to the piezo-electric rod, to transmit a voltage variation corresponding to the oscillating frequency of the vibrating rod to an electronic maintenance oscillator acting on a known device for maintaining vibration of the rod. The resulting device is highly accurate and, because there is no vibration transmitted to the watch casing and wrist band, the timing mechanism is in turn not affected by variable energy transferred from the environment, which would affect the isochronism of the vibrating rod.

United States Patent 1191 1111 3,790,827 I Brunet et a1. Feb. 5, 1974 1 1v PIEZO-ELECTRIC CONTROL DEVICE FOR 2,578,620 12/1951 Wilhelm 310/82 x LOC WO AND THE LIKE TIMING 1,693,806 12/1928 Cady 310/82 X 2,364,681 12/1944 Wright 310/82 X [76] Inventors: Louis C. C. Brunet, Le Bois Jettaz, Primary Examiner j D Miller Le-Vieux; Pierre R. P. Corroyer, 82, 1 9

Avenue de la Plaine y, both Assistant Examiner-Mark O. Budd of France 221 Filed: Nov. 18, 1971- v [57] ABSTRACT I f A piezo-e1ectric control device more particular y or 1 P 199890 clockwork. A vibrating rod is mounted at one end by [30] Foreign Application Priority Data means of a dielectric on the free end of a piezo- '""s'ebiiiiwf"mace ,3, electric rod, the other, end portion of which is supported by a dielectric and flexible elastic bushing on a [52] US. Cl IMO/9.4, 310/82, 310/85 support adapted to be secured to the mounting plate [51] Int. Cl H04! 17/00 of a watch or the like Electrodes are applied to the 3] Field of s r -3, piezoelectric rod, to transmit a voltage variation cor- 53/23 6, 118 responding to the oscillating frequency of the vibrating rod to an electronic maintenance oscillator acting {56] References Cited on a known device for maintaining vibration of the UNITED STATES PATENTS rod. The resulting device is highly accurate and, be- 3 457 463 7/1969 Balamuth .Q 310/82 x caulse is no vibration transmitted to the wawh 3:336:529 8/1967 Tygart 310/82 x Casmg and Wrist band, t timing m h m is in m 2,875,353 2/1959 Cavalieri, Jr. et a1. 3l0/8.2 not affected y variable cnergytransferred from the 2,561,763 7/1951 Waters 310/82 X environment, which would affect the isochronism of 1,866,267 7/1932 Nicolson 310/82 X the vibrating rod. 2,105,011 1/1938 Williams 310/82 2,848,672 8/1958 Harris 318/118 3 Claims, 8 Drawing Figures 3,644,807 2/1972 Zajac 1 3l0/8.1 X 3,657,874 4/1972 lmahashi BIO/8.1 X

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5 FIG. 1. FIG. 3 15 1 INVENTORS LOUIS CvQ. BRUNEI ?|rre RP. CORROYtR PMENTED 74 SHEHEUFZ INVENTORS Lows 0Q BRUNET Plerre R-P-CoR oYER BY I PIEZO-ELECTRIC CONTROL DEVICE FOR CLOCK WORK AND THE LIKE TIMING SYSTEMS The present invention relates to a control device for clockwork and the like timing systems and has for its general object a piezo-electric control device adapted to be associated more particularly with clockwork and enabling to stabilize an electronic clockwork assembly adapted to be mounted in small size time counting devices, such as watches.

Because the device has a vibrating rod or reed which constitutes an excellent time base, the high precision characteristics of this device are used in accordance with the invention to control an electronic oscillator, more particularly a watch electronic oscillator, thus ensuring that the device has a very small frequency variation, in all cases smaller than twice, during a 24 period, the resonant frequency of the vibrating reed. The vibrating reed and its support form a dynamic system with two freedoms of movement. It is known that, when the vibration of the reed is maintained, thesupport transmits the vibration energy to the watch-mounting plate and by conduction to the watch casing and, eventually, to the watch band orbraclet. In certain cases, the assembly of the watch casing and support can start to vibrate in synchronism or in opposite phase with the reed vibration. This mode of operation is therefore highly uncertain. It is affected by variable energy transfers directly depending on the conditions of the casing environment and producing a variation in the fitting characteristics of the reed. Moreover, these forms of reaction disturb the isochronism of the standard vibrating reed.

To overcome these disadvantages, the vibrating reed is, in accordance with the present invention, secured to a piezo-electric rod with interposition of a dielectric sleeve andthe piezo-electric rod is supported in a flexible and elastic member, preferably of plastic material, insuring vibratory damping.

The assembly of the piezo-electric rod and the vibration damping material is secured to the mounting plate of a watch or the like and serves to anchor the vibrating rod or reed.'The latter can thus freely oscillate and the vibrations which the reed produces in the piezo-electric material become useful, because they are not transmitted to the mounting plate, as they are absorbed by the flexible elastic support.

It is known that certain materials, when deformed under purely mechanical external forces, produce an electric polarization. This is the piezo-electric effect. By disposing electrodes along substantially opposed generatrices of a piezo-electric rod to which the vibrating feed is secured, it is easy to collect the electric potential generated by the deformation of the rod under the action of the reed. This electric potential has a sinusoidal form and a frequency precisely equal to the autonomous mechanical oscillating frequency of the vibrating reed. By applying the thus collected potential variation to the control electrodes of one or several transistors of an electronic oscillator serving to maintain the vibrating movement of the reed, one can thus ensure the tripping of the oscillator in perfect synchronism with the frequency of the vibrating reed, and this despite varying conditions in the voltage supplied and the mechanical characteristics of the assembly.

In accordance with a modification of the invention, the piezo-electric rod maintained in the elastic and flexible member and supporting the vibrating reed can have a cross-section in the form of a regular polygon having an even number of sides. Thus, in addition to the two electrodes disposed on the lateral surface of the rod in accordance with substantially opposed generatrices to collect the electric tensions generated by the mechanical deformation of the rod under the action of the reed, one can mount additional electrodes on the-same piezo-electric rod. It is obvious that the lateral faces of the piezo-electric rod receiving the electrodes adapted to collect the potential differences, will necessarily have a definite position with respect to the crystallographic axes of the rod.

In accordance with the invention, the vibrating reed can have very small dimensions and may even be in the form of a simple mass.

The invention will be better understood by referring to the following description and to the annexed schematic drawings which illustrate, in a non-limitative manner, embodiments of the piezo-electric control device in accordance with the invention adaptable more particularly to clockwork. In the drawings:

FIG. 1 is a cross-section of the regulating or control device and showing the reed in side elevation;

FIG. 2 is a top plan view of the device of FIG. 1;

FIG. 3 is a partial elevation of the piezo-electric rod;

FIG. 4 is a top end view of the piezo-electric rod of FIG. 3;

FIG. 5 is a cross-section of a modified control device partially shown and mounted in a support;

FIG. 6 is a schematic cross-section of the piezoelectric rod of the device of FIG. 5;

FIG. 7 is a side elevation of the piezo-electric rod of FIG. 6; and

FIG. 8 is a cross-section of a modified piezo-electric rod.

In FIGS. 1 and 2, a vibrating reed 1 has a non-circular bore 2 at one, end for receiving the free end of a piezoelectric rod 5 with the interposition of a dielectric sleeve 6 to prevent short circuiting of the voltage generated by the mechanical deformations of the piezo electric rod under the constraint produced by the vibration of the reed. The other end portion 8 of the rod 5 is inserted within, and retained, by a flexible, elastic dielectric block 9, or bushing, mounted within and secured to a support 12, said support being secured in turn by means of its holes 13 to, for example, the mounting plate of a watch. It is noted that the reed l is supported by the piezo-electric rod 5.

As shown in FIGS. 3 and 4, a pair of electrodes 14 and 15 respectively are secured to rod 5 in contact with opposed lateral faces thereof along longitudinal opposed generatrices at the end portion 8. These electrodes are at least partially inserted within the vibration damping block 9 and are connected one to a wire 18 and the other to a wire 19, which serve to collect the voltage variation generated by the mechanical deformations of the rod 5, said mechanical deformations being produced by the constraint exerted on the rod by the vibrating reed 1.

It is obvious that the vibrating reed 1 is associated with a device, not shown, serving to maintain the autonomous vibration of the reed and is in turn capable, for example, by means of an escape or ratchet mechanism, not shown, of exerting a mechanical action on the organs of the watch movement.

It is preferred to make the piezo-electric rod 5 with a rectangular cross-section in order to obtain a better fixation of the rod within the bore 2 of reed 1 and within the vibration damping block 9. However, this rectangular cross-section is not essential and can be replaced by any other cross-section, the respective rod receiving bores or cavities in the reed l and block 9 being correspondingly modified. In the same manner, theshape of the block 9 and of the support 12 can be other than circular.

In FIG. 5, the piezo-electric rod 25 has its end 26 inserted within a bore of the vibrating reed 1 with the interposition of a dielectric sleeve 6. The other end portion 28 of the rod 25 is retained in a flexible and elastic block or bushing 27, also made of dielectric material, and serving to dampen vibrations. The end portion 28 of piezoelectric rod 25 has on its lateral faces and along opposed longitudinal generatrices four electrodes shown respectively at 29, 30, 31, and 32 (FIG. 6) which are at least partially inserted within the block 27. These electrodes are each connected to corresponding wires 35 and 36, 37 and 38, allowing to collect the voltages generated by the mechanical deformations of the rod, said deformations being produced by the constraint exerted by the vibrating reed 1.

In accordance with a particular application of the regulating device of FIG. 5, the current collected by electrodes 29 and 32, by means of wires 35 and 38 (see FIGS. 6 and 7), can be used to control an oscillator of the type described in French Patent Application No. E 70:l 2t19ith IYYQQIRLQIWIIOQQQEQQ 3. cor.- responding to other circuits, for example to control or command circuits. In order not to disturb the isochronism of the vibrating reed, the.piezo-electric rod 25 of FIG. 6 is of regular polygonal cross-section with four sides.

Further, for specific use of the piezo-electric rod, the latter can be provided with several electrodes, as shown in FIG. 8. To enable disposing six electrodes 41, 42, 43, 44, 45, and 46, the piezo-electric rod 40 is of regular polygonal cross-section with at least six sides and in the example shown with eight sides with the faces corresponding to sides 48 and 49 serving, for example, for retaining the rod in the vibration damping block 27.

We claim:

1. In a piezo-electric frequency control device for clockwork and the like timing systems, a rod of noncircular cross-section and made of piezo-electric material, a vibrating reed fixed to one end of said piezoelectric rod and extending at substantially right angles thereto and with the interposition of a dielectric, a vibration damping block made of flexible, elastic and dielectric material, in which the other end of said rod is inserted and supported, a rigid support to which said block is secured, said support supporting the entire device and adapted to mount the latter on a mechanism using the device, and at least one pair of electrodes secured to opposite faces of said piezo-electric rod along longitudinal generatrices of said rod to collect current generated thereby, said electrodes being at least partially inserted within said vibration damping block.

2. A device as claimed in claim 1, wherein said piezoelectric rod has a cross-section in the shape of a regular polygon with an even number of sides.

3. In a device as claimed in claim 2, wherein there are at least two pairs of electrodes secured to mutually opposite sides of said rod and occupying a definite position with respect to the crystallographic axes of said rod.

I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3, 790 ,827 Dated February 5, 1974 .Louis C. C. Brunet et a1. Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet [76] "Louis C. C. Brunet, Le Bois Jettaz, Le-Viein'c" should read Louis C. C. Brunet, Le Bois Jettaz AnnecY-Le-Vieux Signed Land sealed this 20th day of August 1974.

' (SEAL) Attest:

MCCOY M. GIBSON, JR. A C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM P0405) ($69) uscofiM-oc scan-poo U75. GOVERNMENT PRINTING OFFICE II! 03S3J4,

UNITED STATES PATENT OFFICE, CERTIFICATE OF CORRECTION Patent No. 79.0 Dated February 5 1974 Inventor(s) .Louis C. C. Brunet et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet [76] "Louis C. C. Brunet, Le Bois Jettaz', Le-VieuX" should read Louis C. C. Brunet, Le Bois Jettaz AnnecY-Le-Vieux Signed and sealed this 20th day of August 1974.

(SEAL) Attest: I

MCCOY M. GIBSON, JR. c. MARSHALL 'DANN Attesting Officer Commissioner of Patents F OHM PO-1050 (10-69) USCOMM-DC 60376-P69 u.s. GOVERNMENT rnmnuo OFFICE n0 o-sss-su. 

1. In a piezo-electric frequency control device for clockwork and the like timing systems, a rod of non-circular cross-section and made of piezo-electric material, a vibrating reed fixed to one end of said piezo-electric rod and extending at substantially right angles thereto and with the interposition of a dielectric, a vibration damping block made of flexible, elastic and dielectric material, in which the other end of said rod is inserted and supported, a rigid support to which said block is secured, said support supporting the entire device and adapted to mount the latter on a mechanism using the device, and at least one pair of electrodes secured to opposite faces of said piezoelectric rod along longitudinal generatrices of said rod to collect current generated thereby, said electrodes being at least partially inserted within said vibration damping block.
 2. A device as claimed in claim 1, wherein said piezo-electric rod has a cross-section in the shape of a regular polygon with an even number of sides.
 3. In a device as claimed in claim 2, wherein there are at least two pairs of electrodes secured to mutually opposite siDes of said rod and occupying a definite position with respect to the crystallographic axes of said rod. 